顯示月份名稱作爲MySQL的列名

Question

我想我的程序裏面如下

year jan  Feb ......Dec 
---- ----- -----  ----- 
2016 val1  val2  val3 
2017 val4  val5 val6 

顯示年月名稱作爲兩個日期之間的列名有一個人幫我做這件事

Answer 1

你可以做這樣的事情，如果我理解你問題正確生成所需的結果集。 TIMESTAMPDIFF(DAY.... + INTERVAL 1 MONTH)可以計算一個月內的天數。 請注意，每個TIMESTAMPDIFF(DAY, '2016-01-01', '2016-01-01' + INTERVAL 1 MONTH) AS 'Jan'行必須正確的月份，它應該工作。

查詢

SELECT 
    '2016' AS YEAR 
, TIMESTAMPDIFF(DAY, '2016-01-01', '2016-01-01' + INTERVAL 1 MONTH) AS 'Jan' 
, TIMESTAMPDIFF(DAY, '2016-02-01', '2016-02-01' + INTERVAL 1 MONTH) AS 'Feb' 
... 
, TIMESTAMPDIFF(DAY, '2016-12-01', '2016-12-01' + INTERVAL 1 MONTH) AS 'Dec' 

UNION ALL 

SELECT 
    '2017' AS YEAR 
, TIMESTAMPDIFF(DAY, '2017-01-01', '2017-01-01' + INTERVAL 1 MONTH) AS 'Jan' 
, TIMESTAMPDIFF(DAY, '2017-02-01', '2017-02-01' + INTERVAL 1 MONTH) AS 'Feb' 
... 
, TIMESTAMPDIFF(DAY, '2017-12-01', '2017-12-01' + INTERVAL 1 MONTH) AS 'Dec' 

結果

year  Jan  Feb  Dec 
------ ------ ------ -------- 
2016  31  29  31 
2017  31  28  31 

或者此查詢使其eazier到新的一年，少代碼重複添加。

查詢

SELECT 
    years.year 
, TIMESTAMPDIFF(DAY, CONCAT(years.year, '-01-01'), CONCAT(years.year, '-01-01') + INTERVAL 1 MONTH) AS 'Jan' 
, TIMESTAMPDIFF(DAY, CONCAT(years.year, '-02-01'), CONCAT(years.year, '-02-01') + INTERVAL 1 MONTH) AS 'Feb' 
... 
, TIMESTAMPDIFF(DAY, CONCAT(years.year, '-12-01'), CONCAT(years.year, '-12-01') + INTERVAL 1 MONTH) AS 'Dec' 
FROM ( 

    SELECT 
    '2016' AS YEAR 

    UNION 
    ALL 

    SELECT 
    '2017' AS YEAR 
) 
AS years 

結果

year  Jan  Feb  Dec 
------ ------ ------ -------- 
2016  31  29  31 
2017  31  28  31